Installing Vinyl over Vinyl

I am down to installing the vinyl in our bathroom. We have vinyl down now and in good shape just outdated, we want to cover the old vinyl with new vinyl. I was reading on the glue that this glue could not be used on vinyl backed carpet so I called the manufacturer. He said not to use this on vinyl or it would turn the old vinyl to mush. If it will do that, won't the fumes from the glue mess the new vinyl up even though it has a backing and we install new 1/4 plywood?

I went back to the supplier today and asked some questions and he got on the phone and they said the same thing he did. The latex all purpose glue I have is what I need. He did tell me if the existing vinyl was embossed that it would show through the new vinyl and he was right but this is a small bath and it won't matter that much, it don't look that bad.